With the increasing attention to multimedia service, radio communication system developers are researching a fourth generation (4G) communication system to increase data rates. For example, 4 G communication technology includes the Wireless Local Area Network (WLAN) proposed by the Institute of Electrical and Electronics Engineers (IEEE) 802.11 Working Group and the Wireless Metropolitan Area Network (WMAN) proposed by the IEEE 802.16 Working Group.
WLAN communications use a short range communication technique developed to provide high-speed communication services to stationary users in a crowded, limited area, such as indoors and downtown, by extending the wired LAN based on the IEEE-802.11 standard. A network which supports the WLAN communications (hereafter, referred to as a WLAN network) supports the users in a service coverage area with tens of Mbps to hundreds of Mbps. However, a WLAN network has narrow service coverage and does not guarantee the mobility of the user.
The WMAN communication technique supports data service based on the IEEE-802.16 standard when users are stationary, walking, or moving at a medium speed (60 km/h at maximum). A network supporting WMAN communications (hereafter, referred to as a WMAN network) supports average data rates of tens of Mbps.
While a WMAN network has wide service coverage and supports user mobility compared to a WLAN network, a WMAN network suffers a low data rate. In contrast, a WLAN network provides a faster data rate than a WMAN network but has narrow service coverage and does not guarantee user mobility. As such, since the multiple networks supported by the broadband wireless communication system have different advantages and disadvantages, service is provided to the user over the corresponding network according to the user's intended service type.
Therefore, to select the network according to the user's intended service type and provide the service to the user, a broadband wireless communication system requires smooth interworkings between networks. That is, the broadband wireless communication system should support a handover between heterogeneous networks or media.